X.Org Version Numbering Schemes

The XFree86 Project, Inc

X.Org has adopted the same basic numbering scheme used by the XFree86
Project, Inc. for their releases. The actual numbers are different, but the
basic scheme is the same. This document reflects the policy that X.Org uses.

Module Versions

Starting with the X11R7.0 release, each module has its own version number.
For those without a natural starting point, the version numbers started at
1.0. For instance, the X11R7.0 release included the xorg-server 1.0
module. As modules are released independently from the rest of the
window system, the module version is the most accurate source of version
information. For instance, there are many X server releases in a year,
but generally only one window system release, so an X server version number
such as 1.7.7 is more informative than the X11R7.5 version for the window
system “katamari” release.

Unfortunately, up through the X server 1.3 release, the X server
used the Window System version when reporting its version number
in log files, the -version option, and the connection setup string
(displayed by xdpyinfo). This was corrected with X server 1.3, which
caused the visible version number string to appear to jump backwards
from 7.2 to 1.3.

Releases, Development Streams and Branches

X.Org has two release branches for the X server software, and several
other modules with active ongoing development.
First is the trunk of the git repository. This is
the main development stream, where all new work and work for future
releases is done.

Second is the stable bugfix branch for the latest full release. It is
created around the time of the release. The branch will be named for the
release version, such as “server-1.9-branch”
for the X server 1.9.x series of releases.
Fixes for bugs found in the release will be added to this branch (as
well as the trunk), and updates to this release (if any) will be cut
from this branch. Similar stable branches are present for previous full
releases.

The X.Org Foundation is planning to make full releases from the main
development stream at regular intervals in the 6-12 month range. The
feature freezes for these releases will usually be 2-3 months before the
release dates. This general plan is a goal, not a binding commitment.
The actual release intervals and dates will depend to a large degree on
the resource available to X.Org.
Update/bugfix releases will be made on an as-required basis,
depending also on the availability of resources, and will generally be
limited to serious bug and security fixes. New features will not
usually be added in update releases.

Aside from actual releases, snapshots of the active release branches
are tagged in the git repository from time to time. Each such snapshot
has an identifiable version number.

Current Version Numbering Scheme

Starting with the main development branch after X11R6.7, the X.Org
versions are numbered according to the scheme outlined here.

The version numbering format is M.m.P.s,
where M is the major version number,
m is the minor version number,
P is the patch level, and
s is the snapshot number.
Full releases have P set to zero, and it is
incremented for each subsequent bug fix release on the post-release
stable branch. The snapshot number s is
present only for between-release snapshots of the development and
stable branches.

Development Branch

Immediately after forming a release stable branch, the patch level
number for the main development branch is bumped to 99, and the snapshot
number is reset. The snapshot number is incremented for each tagged
development snapshot. The git tag for snapshots is
“xorg-server-M.m.P.s”.
When the development branch enters feature
freeze, the snapshot number is bumped to 900. A stable branch may be
created for the next full release at any time after the feature freeze.
When it is, the branch is called
“server-M.m-branch”. The
snapshot number is incremented from there until the release is
finalised. Each of these snapshots is a “release candidate”. When the
release is finalised, the minor version is incremented, the patch level
is set to zero, and the snapshot number removed.

Here's an example which shows the version number sequence for the
development leading up to version 1.8:

1.7.99.1

The first snapshot of the pre-1.8 development branch.

1.7.99.23

The twenty-third snapshot of the pre-1.8 development branch.

1.7.99.900

The start of the 1.8 feature freeze.

1.7.99.903

The third 1.8 release candidate.

1.8.0

The 1.8 release.

1.8.99.1

The first pre-1.9 development snapshot, which is the first main
branch snapshot after creating the 1.8 stable branch.

Stable Branch

After a full release, the stable branch for the release will be
maintained with bug fixes and important updates until the next full
release. Any snapshots on this branch are considered “release
candidates,” which is indicated by setting s
to a number above
900. The snapshot number is incremented for each release candidate
until the update release is finalised. The patch level value
(P) is incremented for each update release.

Here's an example which shows a version number sequence for a 1.8.x
stable branch:

1.8.0

The 1.8 release.

1.8.0.901

The first pre 1.8.1 snapshot.

1.8.0.903

The third pre 1.8.1 snapshot, also known as the third 1.8.1 release
candidate.

1.8.1

The 1.8.1 release.

1.8.1.901

The first pre 1.8.2 snapshot.

1.8.2

The 1.8.2 release.

Finding the X.Org X Server Version From a Client

The X.Org X servers report a VendorRelease value that
matches the X.Org version number. There have been some cases of releases where
this value wasn't set correctly. The rules for interpreting this value
as well as the known exceptions are outlined here.

As noted above, the version reported by VendorRelease
changed from the window system version to the X server version starting in
the xorg-server 1.3 release.

For all X.Org development and release versions using this numbering
scheme, the VendorRelease value is
MMmmPPsss. That is, version
M.m.P.s has VendorRelease set to
M * 10000000 + m * 100000 + P * 1000 + s.

The following is a code fragment taken from xdpyinfo.c
that shows how the VendorRelease information can be
interpreted.